Three-axis offset damping system

ABSTRACT

The present invention comprises a three-axis damping system employing dampers and springs in spatially oriented arrays to isolate an object against translational forces in any direction as well as rotational forces. The inventive system also is biased in the vertical static position to compensate for gravity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing of U.S. ProvisionalPatent Application Ser. No. 60/460,281, entitled “Three-Axis OffsetDamping System,” filed on Apr. 3, 2003, and the specification thereof isincorporated herein by reference.

GOVERNMENT RIGHTS

The U.S. Government has certain rights to this application and inventionpursuant to the terms of Contract No. N-000-19-96C-0128 awarded by theUnited States Navy

BACKGROUND OF THE INVENTION

1. Field of the Invention (Technical Field)

The present invention relates to an apparatus for physically isolatingdelicate or sensitive instrumentation systems, particularly to a dampingapparatus for isolating items or systems from abrupt and potentiallydestructive accelerations.

2. Background Art

There are a variety of contexts in which it is desirable to physicallyisolate items against potentially destructive movements, particularlyrapid accelerations. For example, it is desirable to physically isolatecertain delicate instrumentation in aircraft and missiles, so tominimize the effects of rapid accelerations upon the instruments. Therapid accelerations resulting from abrupt changes in speed and/ordirection of movement may adversely affect the performance of, or evendamage, certain critical devices or systems.

Conventional three-axis isolation systems known in the field of avionicsemploy steel springs to accomplish physical isolation of delicate orsensitive systems. Standard spring-biased systems, however, typicallyoffer little or no damping. For example, there are known TSS Wescam®gimbal systems that are used primarily on police and movie industryhelicopters. These systems use a steel spring and rope systems forisolating cameras. Such systems are not adequate in, for example, harshmilitary environments, where it is difficult to control the isolatedmass of the sensor. Ordinarily, known spring-biased systems are providedwith rubber isolators to give minimal damping characteristics. Theseknown devices perform satisfactorily generally only in thermally stableenvironments. Further, known rubber damper devices have limitedcapabilities when sway space is at a premium or minimal.

Certain avionics systems, when in use, are situated in circumstances ofminimal sway space, and in environments where temperatures may vary overa relatively wide range. Known rubber isolator devices are inadequateunder such conditions. For example, in military applications, there is aneed for fine line-of-sight pointing accuracy while controlling thesensor, despite harsh environmental conditions. A need remains for adamper system for motion-sensitive avionics systems, particularlysystems that require fine pointing accuracies, which are situated inconfined conditions of widely variable environmental temperature.

SUMMARY OF THE INVENTION DISCLOSURE OF THE INVENTION

The invention comprises a three-axis damping apparatus for isolating anobject from the unwanted effect of forces. The apparatus comprises atleast one array of a plurality of shock absorbing dampers interconnectedto at least one array of a plurality of shock absorbing springs to format least one isolator assembly and further comprises a yoke on which toattach the isolator assembly.

The apparatus may comprise two isolator assemblies, and the yoke maycomprise two yoke arms spaced apart from each other at a distancedetermined on the basis of the size of the object to be disposed andprotected between the isolator assemblies. The isolator assemblies aredisposed in parallel orientation to each other, and the yoke arms areadjustably spaced apart at a distance.

The isolator assemblies each further comprise an outer isolator platedisposed adjacent to, and in generally parallel and spaced apartrelation to, an inner isolator plate. The array of dampers and the arrayof springs connect the outer isolator plate to the inner isolator plate.The isolator plates are arranged vertically. Each outer isolator plateis connected to one of the yoke arms and each said inner isolator plateis securely and releasably connected to the object to be protected.

The difference of the distance between the outer isolator plates and thedistance between the inner isolator plates divided by a factor of twomay be approximately equal to the distance between each outer isolatorplate and each adjacent inner isolator plate. The separation of the yokearms holds the outer isolator plates apart from the inner isolatorplates connected to the object to be protected so that the tension ofthe springs is set. The springs and the dampers are arranged to insulatethe inner isolation plates from movement of said outer isolation plates.The dampers ameliorate the rebound effects of the springs.

The invention further comprises a damping isolator assembly comprisingan outer isolation plate comprising a hub, an inner isolation platecomprising a hub, and a plurality of dampers and a plurality of springsconnected to the outer isolator plate and to the inner isolator platethereby connecting the outer isolator plate to the inner isolator plate.

The outer isolator plate hub and the inner isolator plate hub aredisposed in offset relation to each other to compensate for the actionof gravity on the isolator assembly. Further, the outer isolation platecomprises a plurality of ring ridges and corresponding features disposedin an offset relation to the isolator plate's central axis by a distanceapproximately equal to the anticipated shifting distance resulting fromthe weight of a payload.

The dampers may be hydraulic, and the dampers are disposed in pairsadjacent to a pair of the springs. The invention may also comprise aplurality of outer mounts for mounting the dampers to the outer isolatorplate and a plurality of inner mounts for mounting the dampers to theinner isolator plate. The dampers connect from one end to the outermounts and connect from the opposite end to the inner mounts. Thedampers are pivotally connected to the inner isolator plate. The hub ofthe inner isolator plate is connected between the inner damper mount andthe inner isolator plate.

The invention may further comprise a snubber to protect againstcollision between the outer isolator plate and the inner isolator plate,and may be of rubber.

The invention further comprises a method for isolating and protecting anobject from the unwanted effect of forces by disposing the objectbetween isolator assemblies and connecting the isolator assemblies to ayoke which may comprise two arms on for disposing the isolatorassemblies between the two arms.

The method also comprises constructing each isolator assembly byproviding an outer isolator plate, an inner isolator plate, and springsand dampers to connect the outer isolator plate to the inner isolatorplate.

The objects, advantages and novel features, and further scope ofapplicability of the present invention will be set forth in part in thedetailed description to follow, taken in conjunction with theaccompanying drawings, and in part will become apparent to those skilledin the art upon examination of the following, or may be learned bypractice of the invention. The objects and advantages of the inventionmay be realized and attained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate several embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating a preferred embodiment of the invention and are not to beconstrued as limiting the invention. In the drawings:

FIG. 1 is a side perspective view of the apparatus of the invention incontext for use;

FIG. 1A is an inside end (axial) view of a right isolator assemblyaccording to a preferred embodiment of the present invention;

FIG. 1B is a side view of the right side isolator assembly shown in FIG.1A;

FIG. 2A is an inside end (axial) view of a left isolator assemblyaccording to a preferred embodiment of the present invention, typicallyused in combination with the right isolator assembly shown in FIGS. 1Aand 1B;

FIG. 2B is a side view of the right side isolator assembly shown in FIG.2A;

FIG. 3 is an enlarged partial view of the apparatus of the invention asshown in FIG. 1A;

FIG. 4 is the enlarged partial view seen in FIG. 3, rotated to showadditional components of the apparatus;

FIG. 5A is an outside end (axial) view of an outer right isolator plateaccording to the apparatus of the invention;

FIG. 5B is a side sectional view of the isolator plate shown in FIG. 5A,taken along section line B-B in FIG. 5A;

FIG. 6A is an outside end (axial) view of an outer left isolator plateaccording to the apparatus of the invention;

FIG. 6B is a side sectional view of the isolator plate shown in FIG. 6A,taken along section line B-B in FIG. 6A;

FIG. 7A is an outside end (axial) view of an inner right isolator plateaccording to the apparatus of the invention;

FIG. 7B is a side sectional view of the isolator plate shown in FIG. 7A,taken along section line B-B in FIG. 7A;

FIG. 8A is an outside end (axial) view of an inner left isolator plateaccording to the apparatus of the invention;

FIG. 8B is a side sectional view of the isolator plate shown in FIG. 8A,taken along section line B-B in FIG. 8A;

FIG. 9A is an enlarged side (longitudinal) view of a hydraulic dampercomponent of the invention;

FIG. 9B is an end (axial) view of the hydraulic damper shown in FIG. 9A;

FIG. 9C is the hydraulic damper component shown in FIG. 9A, rotatedaxially by 90 degrees to depict added features of the component;

FIG. 9D is a radial sectional view of the damper seen in FIG. 9C, takenalong section line D-D in FIG. 9C;

FIG. 10A is an enlarged partial sectional top view of an outer dampermount component of a preferred embodiment of the present invention,taken along section line A—A in FIG. 10D;

FIG. 10B is a top view of the damper mount component shown in FIG. 10A;

FIG. 10C is a rotated right side view of the damper mount componentshown in FIG. 10B;

FIG. 10D is a front view of the damper mount component shown in 10B;

FIG. 10E is a left side view of the damper mount component shown in FIG.10D;

FIG. 11A is an enlarged partial sectional top view of an inner dampermount component of a preferred embodiment of the present invention,taken along section line A—A in FIG. 11B;

FIG. 11B is a front view of the inner damper mount component shown inFIG. 11A;

FIG. 11C is a right side view of the inner damper mount component shownin FIG. 11B;

FIG. 11D is a perspective, rotated view of the inner damper mountcomponent shown in FIG. 11B;

FIG. 12A is an outside end (axial) view of the assembled right isolatorassembly shown in FIG. 1A, according to a preferred embodiment of thepresent invention;

FIG. 12B is an enlarged, partial, sectional view of the apparatus shownin FIG. 12A, taken along section line B-B in FIG. 12A;

FIG. 12C is a partial side view, taken from vantage line 12-12 in FIG.1A, of the apparatus shown in FIGS. 1A and 12A;

FIG. 12D is an enlarged sectional view of the portion of the apparatusshown in FIG. 12C, taken along section line D-D in FIG. 12 C;

FIG. 13A is an outside end (axial) view of the assembled left isolatorassembly shown in FIG. 2A, according to a preferred embodiment of thepresent invention;

FIG. 13B is an enlarged, partial, sectional view of the apparatus shownin FIG. 13A, taken along section line B-B in FIG. 13A;

FIG. 13C is a partial side view, taken from vantage line 13-13 in FIG.2A, of the apparatus shown in FIGS. 2A and 13A;

FIG. 13D is an enlarged sectional view of the portion of the apparatusshown in FIG. 13C, taken along section line D-D in FIG. 13C;

FIG. 14 is a table setting forth the response of the inventive system inthe vertical, longitudinal, and lateral axes, by natural frequency anddamping percent, at 6 db transmissibility and either 50 W or 80 W oil inthe dampers, for a particular vibratory condition;

FIG. 15 is a graph illustrating the measured vertical axis isolationsystem transmissibility for a certain vibratory condition, withtransmissibility (in db) displayed as a function of frequency (Hz);

FIG. 16 is a graph similar to FIG. 15, except that it illustrates themeasured lateral axis isolation system transmissibility; and

FIG. 17 is a graph similar to FIG. 15, except that it illustrates themeasured longitudinal axis isolation system transmissibility

DESCRIPTION OF THE PREFERRED EMBODIMENTS BEST MODES FOR CARRYING OUT THEINVENTION

The present invention relates to a three-axis damping system employingsmall hydraulic shock absorbers. The shock absorbing dampers arespatially oriented in a unique array to provide damping in anytranslating direction as well as in rotation. The inventive system alsois biased in the vertical static position to compensate for gravity. Theapparatus according to the invention provides a high degree of qualitydamping in an isolation system within a confined space. The inventionretains its optimal damping capability over a wider temperature rangethan any conventional; “elastic” solution. The apparatus finds practicaluse in a variety of contexts where it is desirable to isolatemotion-sensitive devices from deleterious accelerations. It iscontemplated that the invention has beneficial application in advancedavionic systems that require fine pointing accuracy under harshenvironmental conditions.

The inventive system provides high quality damping in three-axistranslation and rotation. The system incorporates small hydraulic shockabsorbers to provide the quality damping. The shock-absorbing hydraulicdampers have ball end joints for free pivoting and rotation toaccommodate relative motion and to compensate for misalignments. Theapparatus of the invention may be fashioned from a durable, rigidmaterial suitable to the particular application; the various componentsmay be machined, for example, from aluminum, stainless steel, ormolybdenum alloys or the like, according to need.

FIG. 1 shows the apparatus of the invention in an instance of use, andprovides context for the further disclosures herein. There is a payloadP which is to be isolated against destructive shocks and accelerations.The apparatus of the invention includes a pair of isolator assemblies100, 100′ which serve this advantageous isolation function. It isdesired to insulate the payload P against abrupt accelerations in anytranslational direction, including longitudinal (i.e. axially towardeither of the assemblies 100, 100′), as well as against deleteriousrotations.

According to the invention, a yoke 103 is provided in which theassemblies 100, 100′ are situated. The yoke 103 may be mounted in anaircraft or other vehicular platform. Yoke 103 has arms 104, 104′ thatare spaced apart at a distance, their distance of separation beingselected according to the size of the payload P and assemblies 100, 100′implemented in the circumstance. While a given yoke 103 may have a baseseparation distance d₁ that is adjustable between uses, the separationdistance d₁ is always securely fixed during any particular use of theinvention.

The isolator assemblies 100, 100′ are each secured, as by bolting, to arespective one of the yoke arms 104, 104′. The assemblies 100, 100′ areeach comprised of an outer isolator plate 120, 120′ and an innerisolator plate 130, 130′. The inner isolator plates 130, 130′ aresecurely, although releasably, connected to the payload P or other itemto be isolated.

Each inner isolator plate 130 or 130′ are in close adjacency with acorresponding outer isolator plate 120, 120′, but adjacent isolatorplates (e.g. 120, 130) are maintained in spaced apart relation. Thevariability of the spacing distance between adjacent isolator platesserves to physically insulate the payload P. As disclosed furtherherein, adjacent isolator plates (e.g. 120, 130 and 120′, 130′) areinterconnected by extension springs and hydraulic dampers which regulatetheir relative motion. The payload P and its mounts define an innerisolation plate separation distance d₂ which, after accounting for thethickness of the isolator plates 120, 130, 120′, 130′ is less than thebase separation distance d₁ so to maintain adjacent isolator plates inspaced relation. Thus, base separation distance d₁ minus the inner plateseparation distance d₂, divided by two, is approximately equal to thespacing distance between adjacent isolator plates. The adjacent isolatorplates 120, 130, and 120′, 130′ are connected by extension springs (intension) and hydraulic dampers, as shall now be further described.

FIGS. 1A, 1B, 2A and 2B illustrate the general configurations ofpreferred embodiments of a pair of isolator assemblies 100, 100′according to the invention, usable in certain avionics applications. Theassemblies 100, 100′ may find beneficial use singly, but extremelypreferably in pairs, e.g., the payload or other item to be isolated isdisposed in contact with, and intermediate to, two assemblies 100, 100′disposed in parallel. The right assembly 100 features two isolatorplates, an outer isolator plate 120 and an inner isolator plate 130,that are disposed in generally parallel relation and movably connectedby various other smaller components of the apparatus as shall be furtherdescribed. The left assembly 100′ is substantially the same inconfiguration and function to the right assembly 100, except asspecifically noted herein. In normal use, the assemblies 100, 100′ aresituated with the isolator plates 120, 130, 120′, 130′ arrangedvertically, as depicted in the figures. The object to be isolated(FIG. 1) is then disposed horizontally between the two assemblies 100,100′, which are spaced apart, with their respective inner isolatorplates 130, 130′ in confronting relation, a suitable distance toaccommodate the object. The object to be isolated is attachable to theinner isolator plates. The assemblies 100, 100′ themselves arerespectively anchored, by the outer isolator plates 130, 130′, to theyoke which is mounted in the vehicle or platform in use.

In sum, the separation of the yoke arms 104,104′ effectively holdsadjacent isolator plates apart, and sets the spring tension. An offset,further described herein, in the hubs of the isolator plates compensatesfor gravity; there is a slight sag in the extension springs when thepayload is attached. Thus, the isolator plate hubs are offset under noload, and go to the center of travel when the payload is installed.

Reference to FIGS. 1A, 1B, 2A and 2B show, in addition to the outerisolator plates 120, 120′ and inner isolator plates 130, 130′, thearrangement of the array of extension springs 132, 132′, 132″ andhydraulic dampers 142, 142′, 142″. The springs and dampers are speciallyarranged to insulate the inner isolation plates 130, 130′ from anyjarring movement of the outer isolation plates 120, 120′, as furtherdisclosed herein.

Attention is invited to FIGS. 3 and 4, showing, in enlarged partialviews, that an isolator assembly 100 has the outer isolator plate 120disposed generally parallel to the inner isolator plate 130. FIG. 3 isan inside normal view of the isolator assembly 100, whereby the systemto be isolated (not shown) is mounted, e.g. by bolting, to the innerisolator plate 130. As seen in the figures, translational and rotationalisolation of the inner isolator plate 130 in relation to the outerisolator plate 120 is provided by the plurality (preferably fourteen) ofextension springs 132, 132′. The figures also depict four of theplurality of hydraulic dampers 142, 142′ according to the inventionconnecting the inner isolator plate 130 to the outer isolator plate 120.Adjacent pairs of dampers are connected to the outer isolator plate 120by means of custom outer damper mounts 170 (FIG. 4), to be furtherdescribed, attached to the outer isolator plate 120. In the preferredembodiment, fourteen dampers 142 are attached using seven outer dampermounts 170. The ends of the dampers opposite from the outer dampermounts are connected to the inner isolator plate 130 by means of innerdamper mounts 180 (FIG. 3), also preferably seven in number and to befurther described herein, attached to the inner isolator plate 130.

The preferred configuration of the right outer isolator plate 120, forconstruction of the right isolator assembly 100, is depicted in FIGS. 5Aand 5B. The very similar left outer isolator plate 120′ is depicted inFIGS. 6A and 6B. Like portions of the respective isolator plates 120,120′ are identified using like numerical labels; description of theright outer isolator plate 120 thus serves to describe correspondingportions of the left outer isolator plate 120′. The outer isolatorplates 120, 120′ may be sized according to need, and may have an outsidediameter (as defined by outer flange 126) of, for example, approximatelynine inches. Outer isolator plates 120, 120′ preferably are machinedfrom aluminum alloy 6061-T651 or suitable alternatives.

Somewhat disk-like outer isolator plate 120 features a generallycylindrical hub 122 having a principal inside diameter of, for example,about 4.8 inches. Extending radially inward from the hub 122 is anannular inner flange 123 defining a circular axial aperture 124completely penetrating the plate 120. Axial aperture may have a diameterof, for example, about 3.6 inches. The inner flange 123 also defines onits upper surface a shoulder 125, so that the inner wall of the hub 122above the inner flange defines a basin having a deep (e.g. about 0.84inch) upper portion above a shallower (e.g. 0.16 inch) lower portion,the lower portion having a comparatively smaller diameter (e.g.approximately 4.4 inches), as seen in FIGS. 5A and 5B. The annulus ofthe inner flange 123 is penetrated between the shoulder 125 and theaxial aperture 124 by an array of six (preferably) equally spacedfastener apertures 128, 128′ as seen in FIG. 5A. Below the inner flange123, the inner wall of the hub 122 defines an inverted basin having adiameter (e.g. approximately 4.8 inches) corresponding to the upperportion of the upper basin.

Extending radially outward from the upper portion of the hub 122 is anannular outer flange 126. The disk-like outer flange 126 has thestylized cross section illustrated in FIG. 5B. Protruding upward fromthe outer flange 126 is circular ring ridge 133, which defines the uppertable 127 on the upper surface of the flange 126. As indicated in thefigures, the ring ridge 133 is not coaxial with the hub 122. Thedefinitional axis of the ring ridge 133 is parallel to, but offset from,the axis of the hub 122 by, for example, approximately 14% of the radiusof the ring ridge 133. Thus, as best seen in FIG. 5A, the table 127 isoff-center from the hub 122 in a cam-like manner, with the table 127being broader on one side of the hub's axis than on the other side. Theouter flange 126 is penetrated by nine non-equally space apertures 129,129′, 129″ in the circumferential array shown in FIGS. 5A and 6A, whichmay be used to secure the assembly 100 to the yoke 103 (FIG. 1). In thepreferred embodiment, the outer flange 126 also features a plurality,preferably seven, equally spaced groups of three connection apertures138, 138′, 138″, also as seen in FIGS. 5A and 6A. Connection apertures138, 138′, 138′″ are employed in the connection of the hydraulic dampers142, 142′ to the outer isolator plate 120, as further disclosedhereafter.

Reference to FIGS. 6A and 6B shows that the left outer isolator plate120′ is substantially similar to the right outer isolator plate 120. Itis a reflection, with the ring ridge 133′ offset in a complementarydirection from that of the right outer isolation plate 120. Further, asseen in FIG. 6B, the inner flange 123′ extends inwardly from the wall ofthe hub 122′, but at a medial vertical position so as to divide theinterior of the interior of the hub more nearly in half, with the upperbasin being not quite as deep as the inverted lower basin. The innerflange 123′ defines the axial aperture 124. The overall principaldimensions of the various features of the left outer isolator platecorrespond generally to those of the right outer isolation plate 120.

FIGS. 7A and 7B illustrate the right inner isolator plate 130, whileFIGS. 8A and 8B depict the left inner isolator plate 130′. As thesefigures show, the two inner isolator plates 130, 130′ are substantiallyidentical. The inner isolator plates 130, 130′ preferably are machinedfrom aluminum alloy 6061-T651 or suitable alternatives. With outerisolator plates 120, 120′ having diameters of approximately 9.0 inches,for example, the inner isolator plates 130, 130′ may have slightlylarger overall diameters, for example approximately 11.5 inches asdefined by rim 145. As indicated in the figures, the inner isolatorplates 130, 130′ are configured much like a wheel with spokes. Acylindrical wall defines the hub 140, 140′ from which extend radiallythe plurality of integral spokes 142, 142′, 142″, preferably six innumber. In the preferred embodiment being specifically described, thehub 140 has an inside diameter of, for example, approximately 6.0inches, and a depth of about 1.2 inches. A plurality, preferably seven,of groups of connection apertures 139, 139′, 139″, 139′″ are equallyspaced around, and defined through, the wall of the hub 140 or 140′ forconnection of the hydraulic dampers 142 to the inner isolator plates asfurther described herein.

Each of the spokes 142, 142′, 142″ has a reinforcing flange 149 runningcentrally and longitudinally. The spokes 142, 142′, 142″ support thecircular rim 145, 145′ in concentric spaced relation from the hub 140 or140′. The hub 140 or 140′ of each of the inner isolator plates 130, 130′has a floor 146, 146′, which in turn defines a central aperture 147,147′. The apertures 147, 147′ have diameters of, for example, about 1.5inches. The rim 145 or 145′ is provided with various connectorattachment holes 148, 148′, arranged as seen in FIGS. 7A and 8A. Aplurality, such as eight, hub attachment holes 151, 151′ penetrate thefloor 146, 146′ of each plate 130, 130′ in a radial array around therespective central aperture 147 or 147′, as best indicated in FIGS. 7Aand 8A. The attachment holes 151, 151′ may be used to fasten the objectto be isolated to the inner isolation plate 130 or 130′.

It is seen that the offset character of the hub tables 127, 127′, inrelation to the axes of the hubs 122, 122′, of the outer isolator plates120, 120′ supplies a means for providing balanced concentricity of thevarious components of each assembly 100, 100′ despite the effects ofgravity. The loading of a payload to be protected, e.g. an approximately85-lb instruments package, causes the inner isolation plates 130, 130′to shift downward, against the bias of the extension springs, relativeto the outer isolation plates 120, 130. Using known methods ofcalculation, this shifting distance, or “sag,” can be predetermined, andthe degree of offset embodied in the outer isolator plates 120, 120′fashioned to correspond to the shifting distance. (The measure of theoffset is calculated based upon, among other things, primarily theweight of the payload.) An aspect of the invention, thus, is thecustomized construction of outer isolation plates 120, 120′ having ringridges 133,133′ and corresponding features that are offset from theisolator plates' central axis a distance approximately equal to theanticipated shifting distance resulting from the weight of theidentified payload.

The outer isolation plates 120, 120′ are mounted vertically (on theirrespective yoke bases) with their respective ring ridges 133, 133′offset downward, i.e., with the broadest portion of the table 127, 127′registered at the 6:00 o'clock position. With these eccentricities ofthe outer isolation plates 120, 120′ thus aligned in the direction ofthe vertical gravity vector, when the inner isolation plates 130, 130′are loaded with the payload, the central axis of the inner isolationplates 130, 130′ moves downward. This downward movement is over adistance equal to the predetermined shifting distance, and thus bringsthe central axes of all isolator plates 120, 120′, 130, 130′ intoalignment. The principal components of the assemblies 100, 100′consequently are placed into coaxial registration, so that the isolatorassemblies thereafter operate and function symmetrically.

The inner isolator plates 130, 130′ are attached to the respective outerisolator plates 120, 120′ by, among other things, a plurality ofextension springs 132, 132′, as seen in, for example, FIGS. 1A, 1B, 2Aand 2B, 12A-D, and 13A-13D. In the preferred embodiment, the extensionsprings 132, 132′ number fourteen, although the apparatus can becustomized in size and therefore require more or less than this numberof extension springs. The extension springs 132, 132′ are, however,always arranged in pairs as indicated in the drawing figures. Eachspring 132 preferably is manufactured from material 17-7PH CRES, to havea spring rate, in one preferred embodiment, of approximately 35±3lb/inch, and a diameter of about one-half inch with a free length ofapproximately 1.66 inches. The extended length preferably is about 2.41inches, at an initial tension, when installed, of approximately 7.8 lbsand a load at the extended length of about 31.6 lbs. The terminal hooksof one spring from each installed pair preferably are radially offsetfrom each other by approximately 90°, while the other spring of the pairpreferably has terminal hooks in mutual alignment. Suitable springs areavailable from Associated Spring Raymond, Maumee, Ohio, USA, as partnumbers E19-060302-20-BDC and E19-060602-01-BDC.

FIGS. 9A-D depict the preferred hydraulic damper component for use inthe inventive apparatus. In the preferred embodiment, the dampers 142,142′ number fourteen, although the apparatus can be customized in sizeand therefore require more or less than this number of dampers. Thehydraulic dampers 142, 142′ are, however, always arranged in pairs asindicated in the drawing figures. Referring to FIGS. 9A-D, each damper142 is of generally conventional construction, having a closed hydrauliccylinder 160 from which the movable (damped) rod 161 extends under thedamping influence of the piston within the cylinder 160 (FIGS. 12D and13D). A base ring 162 is secured to the end of the cylinder 160, whilethe operative eyelet 164 is secured to, or integral with, the movablerod 161.

Each hydraulic damper 142 preferably meets performance standardsaccording to the given application. In the preferred embodiment, thedamper 142 shall meet all performance standards over the temperaturerange of −40° C. to 70° C. The plurality of dampers incorporated intothe inventive apparatus shall have consistent, substantially performancespecifications. Thus, in a complete pair of assemblies 100, 100′ thevarious dampers shall be, for example matched sets of 28 units, with noindividual damper in the set deviating more than 10% from the averagedamping coefficient of the set. In one preferred embodiment, each damper142 preferably has a minimum damping coefficient of 0.6 lb-sec/inch whensubjected to cyclic displacements of ±0.006 through ±0.050 inches withfrequencies of 5 to 10 Hz. Over this range of displacements andfrequencies, the damping preferably is approximately viscous incharacter. The energy loss per cycle is consistent with that expectedaccording to known viscous damping laws.

The force generated by a damper 142 is such that it does not exceed thatexpected by viscous damping laws for cyclic displacements less than±0.005 inch and frequencies from about 20 to about 100 Hz for thedamping coefficient determined according to the specifications above.The center position (center of base ring 162 to center of eyelet 164, 1in FIG. 9C) is about 2 inches, and the damper 142 preferably allows astroke of ±0.34 inch from the center position. Preferably, the dampermeets the performance requirements disclosed above for any pistonposition within approximately ±0.275 inch of the center position. Also,the damper 142 preferably exhibits no more than approximately 0.5 lbstiction prior to initial piston breakaway. The damper 142 ideallypossesses less than 10 lb/inch residual stiffness for any of theforegoing conditions, as determined by the phase shift of the damperforce relative to the input displacement. Further, in the preferredembodiment, the damper 142 shall not be damaged when subjected to amaximum transient shock velocity of 30 inches/sec applied for a minimumduration of 0.005 seconds. The performance of each damper 142 preferablyis not appreciably affected by its orientation relative to the gravityvector. Respecting component longevity, it is preferred that the damper142 maintains at least 50% of the damping capacity defined above, afterexposure to the following vibrations: ±0.035 inches at 7.5 Hz for 8,500hours; ±0.080 inches at 7.5 Hz for 1,400 hours; and ±0.125 inches at 7.5Hz for 100 hours. A suitable hydraulic damper 142 is available fromEnidine, Inc., Orchard Park, N.Y., USA, as part number SP21847.

The apparatus of the invention includes customized mounts for mountingthe plurality of hydraulic dampers 142, 142′ to the inner and outerisolator plates 120, 120′, 130, 130′ of the respective isolatorassemblies 100, 100′. Collective reference is made to FIGS. 10A-E, whichdepict one outer damper mount 170 that preferably is used to pivotallysecure a hydraulic damper 142 to the outer isolator plate 120. The outermount 170 features a base flange 172 penetrated by at least one, andpreferably three, fastener apertures 173, 173′, 173″. Fastener apertures173, 173′, 173″ permit a bolt or screw or other fastener to be used tosecurely connect the mount 170 to the outer isolator plate 120. In thepreferred embodiment, the outer damper mount 170 is secured to the outerisolator plate 120 or 120′ by means of the passage of screws or boltsthrough the fastener apertures 173, 173′, 173″ for threaded engagementinto a corresponding group of connection apertures 138, 138′, 138′″ inthe inside face of the outer isolator plate 120 or 120′, as seen inFIGS. 4, 5A and 6A. Each outer mount 170 also features a projectingbezel 175 into which a pair of fastener holes 177, 177′ are tapped. Asbest seen in FIG. 10A, the outer mount fastener holes are provided in amutually angled orientation. The fastener holes 177, 177′ permit a screwor bolt or pin, for example, to be passed through the base ring 162 ofthe damper 142 and inserted, as by threaded engagement, into arespective one of the holes 177 or 177′ to connect the damper 142 to theouter isolator plate 120, as seen in FIGS. 12D and 13D.

Combined reference is made to drawing FIGS. 11A-11D, depicting apreferred inner damper mount 180 by which the inner end of a hydraulicdamper 142 is connected to the inner isolator plate 130 or 130′. Theinner mount 180 features a base flange 182 penetrated by at least oneand preferably four fastener apertures 183, 183′, 183″, 180′″. Fastenerapertures 183, 183′, 183″, 183′″ permit a bolt or screw or otherfastener to be used to securely connect the mount 180 to the innerisolator plate 130. In the preferred embodiment, the inner damper mount180 is secured to the inner isolator plate 130 or 130′ by means of thepassage of screws or bolts (not shown) through the fastener apertures183, 183′, 183″, 183′″ for threaded engagement into a correspondinggroup of connection apertures 139, 139′, 139″, 139′″ in the hub 140 ofthe inner isolator plate 130 or 130′, as seen in FIGS. 7B and 8B, andfurther suggested in FIGS. 12B and 13B. Each inner mount 180 alsofeatures a pair of projecting angled flanges 185, 185′ into which afastener hole 187, 187′ is defined. As best seen in FIG. 11A, the outermount flanges 185, 185′ are provided in a mutually angled orientation.The fastener holes 187, 187′ permit a screw or bolt or pin, for example,to be passed through the base ring 164 of the damper 142 and insertedthrough a respective one of the holes 187 or 187′. Since the mount 180is fixed to the inner isolator plate 130 or 130′, such a pinnedconnection of the damper 142 to the mount 180 serves to pivotallyconnect the damper to the inner isolator plate 130 (FIGS. 12D and 13D).

FIG. 12A is an outside end view of the right isolator assembly 100(depicted from an inside end view in FIG. 1A). FIG. 12A shows, amongother things, the various holes and apertures in the isolator plates120, 130 used to attach the outer damper mounts 170 to the outerisolator plate, and with which the extension springs 132, 132′ areconnected to the inner isolator plate. Combined reference to FIGS. 4 and5B, for example, illustrate how the in the preferred embodiment, theouter damper mount 170 is secured to the outer isolator plate 120 byinserting fasteners through the outer damper mount and into acorresponding group (e.g. three) of connection apertures 138, 138′,138′″ in the outer isolator plate. Similarly, combined reference toFIGS. 3, 4, and 7B suggest how, the in the preferred embodiment, theinner damper mount 180 is secured to the inner isolator plate 130 byinserting fasteners through the inner damper mount and into acorresponding group (e.g. four) of connection apertures 139, 139′, 139″,139′″ in the hub 140 of the inner isolator plate 130. FIGS. 3 and 4 showthe use of special brackets 190, connected to the rim 145 of the innerisolator plate 130 using the various connector attachment holes 148,148′ seen in FIG. 7A, to attach the extension springs 132, 132′ to theinner isolator plate. Apertures 192 in the periphery of the outerisolator plate 120 (FIG. 5A), connect the other ends of the springs 132,132′ to the outer isolator plate.

FIGS. 12A-D provide added detail concerning the positional relationshipsand interconnections between the right inner isolator plate 130, theright outer isolator plate 120, and a hydraulic damper 142, when theright isolator assembly 100 is properly assembled for use. FIG. 12B isan enlarged partial side view of the assembly 100 seen in FIG. 12A. FIG.12B is an enlarged sectional view of the apparatus depicted in FIG. 12A,taken along section line B-B in FIG. 12A. FIG. 12D is an enlargedsectional view of the apparatus depicted in FIG. 12C, taken alongsection line D-D in FIG. 12C. Particular attention is invited to FIG.12B, which shows the situation of the right outer isolation plate 120parallel adjacent to the right inner isolation plate 130, with the hub122 of the outer plate 120 inserted concentrically within the basindefined by the hub 140 of the inner plate 130. Combined action of theextension springs 132 and hydraulic dampers 142 serve to maintain theisolator plates 120, 130 in close adjacency as seen in FIGS. 12B and12C.

A rubber snubber 200 protects against damaging collision between theisolator plates 120, 130 in the event the system is “overdriven” byunexpectedly high accelerations. Nevertheless, the extension springs 132and hydraulic dampers 142 normally serve to insulate or isolate theinner isolator plate 130 from movements of the outer isolator plate 120.The snubber 200 is located at the isolator plates' “end of travel,” sothat in the vent of a catastrophic incident, such as hard landings (ascan be anticipated to have, for example, three hours or less durationover the expected 10,000 hour life expectancy of the apparatus), or in aparticularly extreme combination of concurrent acceleration events, theisolator plates engage the snubber 200 to provide redundant or addedshock absorbency for payload protection.

FIGS. 13A-D are substantially similar to FIGS. 12A-D, but serve to showthe relationships among the various components of the left assembly 100′of a pair of assemblies 100, 100′. A left isolator assembly 100′ has aleft inner isolator plate 130′, a left outer isolator plate 120′, and ahydraulic damper 142. FIG. 13B is an enlarged partial side view of theassembly 100′ seen in FIG. 13A. FIG. 13B is an enlarged sectional viewof the apparatus depicted in FIG. 13A, taken along section line B-B inFIG. 13A. FIG. 13D is an enlarged sectional view of the apparatusdepicted in FIG. 13C, taken along section line D-D in FIG. 13C. FIG. 12Bshows the situation of the left outer isolation plate 120′ paralleladjacent to the left inner isolation plate 130′, with the hub 122′ ofthe outer plate 120′ inserted concentrically within the basin defined bythe hub 140′ of the inner plate 130′. Combined action of the extensionsprings 132 and hydraulic dampers 142 serve to maintain the leftisolator plates 120′, 130′ in close adjacency as seen in FIGS. 13B and13C. Nevertheless, the extension springs 132 and hydraulic dampers 142likewise serve to insulate or isolate the inner isolator plate 130′ frommovements of the outer isolator plate 120′.

It is seen, therefore, that the assembled system according to thepresent invention overcomes the disadvantages isolation systemsemploying undamped spring bias. When properly assembled and loaded, theinner 130, 130′ and outer 120, 120′ isolator plates are coaxiallyaligned. The assembles thereafter function in a symmetric fashion, withthe inner isolator plates 130, 130′ suspended in spaced relation fromthe outer isolator plates 120, 120′. Abrupt movement (translational orrotational) of the outer isolator plates 120, 120′ is not immediatelyimparted to the inner isolator plates 130, 130′, thus protecting thepayload from rapid acceleration. Deleterious rebound effects due to theaction of the extension springs 132 is ameliorated by the dampers 142.The circumferential array of springs and dampers, arranged inconfronting pairs as described, insulate the inner isolator plates, andthus the payload, from acceleration in practically any direction, with“sway” contained in a relatively confined space.

INDUSTRIAL APPLICABILITY

The invention is further illustrated by the following non-limitingexamples.

Example 1

A three-axis offset damping system was constructed generally inaccordance with the foregoing description. The hydraulic damperscontained 80-weight oil in one example, or 50-weight oil in anotherexample. The payload weighed approximately 84.1 lbs. The system wassubjected to a randomly selected one of a series of controlled vibratoryenvironmental conditions, and the system response was measured. Thedrawing figures described below thus pertain to only one of a vast setof possible environmental vibratory conditions and are offered only byway of example to demonstrate the effectiveness of the invention.

FIG. 14 is a table setting forth the response of the system in thevertical, longitudinal, and lateral axes, by natural frequency anddamping percent, at 6 db transmissibility and either 50 W or 80 W oil inthe dampers. A “control” was run using only extension springs, withoutany dampers. Combined reference to FIGS. 14-17 shows marked improvementin system response with dampers installed using 80 W oil.

FIG. 15 is a graph illustrating the measured vertical axis isolationsystem transmissibility. The system had an initial configuration with 38lb/in extension springs and 80 W damper oil. With the system subjectedto Group 1-21 vibration, transmissibility (in db) displayed as afunction of frequency (Hz). Also charted are curves generated for anundamped system at 12.5 Hz, and with a viscous damper at 12.5 Hz and21.8% damping.

FIG. 16 is a graph illustrating the measured lateral axis isolationsystem transmissibility. The system had an initial configuration with 38lb/in extension springs and 80 W damper oil. With the system subjectedto Group 1-21 vibration, transmissibility (in db) is displayed as afunction of frequency (Hz). Also charted are curves generated for anundamped system at 11 Hz, and with a viscous damper at 11 Hz and 21.8%damping.

FIG. 17 is a graph illustrating the measured longitudinal axis isolationsystem transmissibility. The system had an initial configuration with 38lb/in extension springs and 80 W damper oil. With the system subjectedto Group 1-21 vibration, transmissibility (in db) is displayed as afunction of frequency (Hz). Also charted are curves generated for anundamped system at 11.2 Hz, and with a viscous damper at 11.2 Hz and21.8% damping.

The preceding example can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

Although the invention has been described in detail with particularreference to these preferred embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverall such modifications and equivalents. The entire disclosures of allreferences, applications, patents, and publications cited above arehereby incorporated by reference.

1. A damping isolator assembly comprising: an outer isolation platecomprising a hub and a plurality of ring ridges and correspondingfeatures, said ridges offset from a central axis of said outer isolatorplate by a distance approximately equal to an anticipated shiftingdistance resulting from the weight of a payload; an inner isolationplate comprising a hub; a plurality of dampers connecting said outerisolator plate to said inner isolator plate; and a plurality of springsconnecting said outer isolator plate to said inner isolator plate, saiddampers and said springs being connected to said outer isolator plateand said inner isolator plate at locations distinct from one another. 2.The apparatus of claim 1 wherein said outer isolator plate hub and saidinner isolator plate hub are disposed in offset relation to each otherto compensate for the force of gravity on said isolator assembly.
 3. Theapparatus of claim 1 wherein said dampers comprise hydraulic dampers. 4.The apparatus of claim 1 wherein a pair of said dampers are disposedadjacent to a pair of said springs.
 5. The apparatus of claim 1 furthercomprising a plurality of outer mounts for mounting said plurality ofdampers to said outer isolator plate and a plurality of inner mounts formounting said plurality of dampers to said inner isolator plate.
 6. Theapparatus of claim 1 wherein said dampers are pivotally connected tosaid inner isolator plate.
 7. The apparatus of claim 5 wherein said hubof said inner isolator plate is connectedly disposed between one of saidplurality of said inner damper mounts and said inner isolator plate. 8.The apparatus of claim 1 further comprising a snubber to protect againstcollision between said outer isolator plate and said inner isolatorplate.
 9. A damping isolator assembly comprising: an outer isolationplate comprising a hub; an inner isolation plate comprising a hub; aplurality of dampers connecting said outer isolator plate to said innerisolator plate; a plurality of springs connecting said outer isolatorplate to said inner isolator plate, said dampers and said springs beingconnected to said outer isolator plate and said inner isolator plate atlocations distinct from one another; and a rubber snubber to protectagainst collision between said outer isolator plate and said innerisolator plate.
 10. The apparatus of claim 9 wherein said outer isolatorplate hub and said inner isolator plate hub are disposed in offsetrelation to each other to compensate for the force of gravity on saidisolator assembly.
 11. The apparatus of claim 9 wherein said outerisolation plate comprises a plurality of ring ridges and correspondingfeatures, said ridges offset from a central axis of said outer isolatorplate by a distance approximately equal to an anticipated shiftingdistance resulting from the weight of a payload.
 12. The apparatus ofclaim 9 wherein said dampers comprise hydraulic dampers.
 13. Theapparatus of claim 9 wherein a pair of said dampers are disposedadjacent to a pair of said springs.
 14. The apparatus of claim 9 furthercomprising a plurality of outer mounts for mounting said plurality ofdampers to said outer isolator plate and a plurality of inner mounts formounting said plurality of dampers to said inner isolator plate.
 15. Theapparatus of claim 9 wherein said dampers are pivotally connected tosaid inner isolator plate.
 16. The apparatus of claim 9 wherein said hubof said inner isolator plate is connectedly disposed between said innerdamper mount and said inner isolator plate.
 17. A method for isolatingand protecting an object from the unwanted effect of forces comprisingthe steps of: constructing isolator assemblies by: providing an outerisolator plate comprising a plurality of ring ridges and correspondingfeatures, said ridges offset from a central axis of said outer isolatorplate by a distance approximately equal to an anticipated shiftingdistance resulting from the weight of a payload; providing an innerisolator plate; and providing a plurality of springs and dampers toconnect the outer isolator plate to the inner isolator plate, saidsprings and dampers connected to said outer isolator plate and saidinner isolator plate at distinct locations; disposing the object betweenisolator assemblies; and connecting the isolator assemblies to a yoke.18. The method of claim 17 further comprising the step of providing twoarms on the yoke and disposing the isolator assemblies between the twoarms.